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Thread: Dual Fiamm Horns on r90/6 with relay

  1. #1
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    Dual Fiamm Horns on r90/6 with relay

    Hi All,

    My horn recently failed, so I've purchased 2 Fiamms (one high & one low). I've been looking online for instructions and have found numerous posts about using a relay, so I got a relay: Bosch 0-332-209-158.

    Here's what I'm encountering:

    1. Connect 1 horn to the existing wiring - nothing
    2. Connect 1 horn to just the hot wire and ground to frame - BEEP (without pushing Horn button)

    3. Connect both horns through relay: hot on 86+, ground on 85, 12v from battery with 20 amp fuse on 30, connect both horns to 87a - BEEP (without pushing Horn button

    4. Connect both horns the same as #3 but instead of 87a for the connection to the horns, I connected them to 87 - nothing

    What is going on here? I have continuity at the hot wire at the output from the horn and at the horn switch, nothing seems to be shorting out.

    Any ideas... ??

    Thanks!

    Kevin
    R90/6 - 1976

  2. #2
    Registered User donbmw's Avatar
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    When I installed The RS fairing on my 75 R90/6 I added the dual horns. I had to add and ground wire from the center mounting bolt on the horns to the bike frame and all work as needed. Will look tonite when I get home and check wires at relay since I have the tank off.

    Don
    1975 R90/6, 1980 and 1982 R65, !959 TR3A Triumph Car

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    Thanks Don! Upon further inspection it seems that I may have a fault on the ground coming from the horn button, I'm not getting a continuity light on that ground wire... That MAY just be my issue, I would still like to know how yours is wired. There is zero info online about wiring dual horns on an old airhead. Are you using a relay with an open connection, 87a?

    Kevin
    R90/6 - 1976

  4. #4
    Registered User donbmw's Avatar
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    Just looked at my bike. Connections 30 and 87 are the control for the relay. I installed the original horn wire to these. It does not matter as to which wire goes to them. Connection 85 and 86 are to power the horns. The two power wires for the horns go to one of them and I had splice in the the main power wire of the bike for power to the relay for the horn on the other connection. Then run ground wires from the center mount bolt to the frame ground. The wire diagrams starting for the 77 RS and has this wired with the relays and had used this for how I wired mine. I believe Snowbum's site has wire diagrams that you should be able to download. I downloaded them for my R90 and R65 had them inlarged so it would be easy to see and follow.

    Don
    Last edited by donbmw; 04-23-2013 at 02:18 AM.
    1975 R90/6, 1980 and 1982 R65, !959 TR3A Triumph Car

  5. #5
    Registered User lmo1131's Avatar
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    Kevin, unlike the /5, there is no "ground" wire coming from the horn button. The horn is grounded, power comes from the horn button (via fuse 15).

    Green/Black from the fuse to the horn button; Brown/Black from the horn button to the horn.

    Am I misunderstanding you?



    and this... obviously for an automobile, but the logic is the same.

    edit - well, the logic is the same if what you want to do is be able to switch from "city" horns to "highway" horns.

    Disregard the SPDT switch in the diagram.

    Last edited by lmo1131; 04-23-2013 at 02:56 PM.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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    Registered User donbmw's Avatar
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    I just checked Snowbum's site it does not show a diagram with dual horns. The Clymers manual I have shows the 77 and 78 RS's having relays and being only years that had relays for the horns.

    Don
    1975 R90/6, 1980 and 1982 R65, !959 TR3A Triumph Car

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    Quote Originally Posted by lmo1131 View Post
    Kevin, unlike the /5, there is no "ground" wire coming from the horn button. The horn is grounded, power comes from the horn button (via fuse 15).

    Green/Black from the fuse to the horn button; Brown/Black from the horn button to the horn.

    Am I misunderstanding you?
    I made a mistake in reading the wiring and the diagram and was confusing the brown/white for ground. I have a continuity on the green/black, but none on the brown/black at the output to the horn. I must have a fault somewhere. I'll have to do some searching today and see if I can find where the fault is.


    Thanks for the clarification, much appreciated.

    Kevin
    R90/6 - 1976

  8. #8
    Registered User lmo1131's Avatar
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    Kevin

    There is a discrepancy on the wiring diagram that I posted. The wire running from the switch to the "H" terminal on the fuse block (contact plate) is BR/WS (brown/white) NOT BR/SW (Brown/Black (as I noted above)). The wire running from the fuse block to the horn SHOULD BE BR/WS (brown/white) as well. The "S" and the "W" have been transposed.

    I would check this terminal for tightness and corrosion.

    A wiring caveat...

    Comparing several "/6" wiring diagrams it appears that the horn has, on some models, been wired as "hot" with the horn button providing the path to ground. I actually think this is the better practice, but I'm somewhat at a loss to explain why it went back and forth. It works either way ... just be aware that your bike may be wired either way.

    Here's a recently posted "new" /6 wiring diagram (that I had not seen before) showing the horn "hot" with ground through the button > http://r90sclub.dudley.nu/Articles/R...ng+Diagram.pdf

    A 1975 "/6" wiring diagram from Snobum's site showing the horn "hot" (with "ground" coming through the switch via Terminal 31 (brown)) > http://bmwmotorcycletech.info/schematic1975,1976.htm

    A then, a 1978 "/7" diagram showing the horn again "grounded" (with 12v coming through the horn button via Terminal 15) > http://mrmorksmotorcycle.com/?paged=2
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    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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